Viscous liquid type seam tester



June l, 1954 o. E. ANDRUS ,679,747 VISCOUS LIQUID TYPE SEAM TESTER FiledMarch 31, 1950 FIG]. 7 :9

INVENTOR. Orrzn E. Andrus. BY

ATTORNEYS.

Patented June 1, 1954 S PATENT OFFICE VISCOUS LIQUID TYPE SEAM TESTERGrrin E. Andrus, Milwaukee, Wis., assignor to A. 0. Smith Corporation,Milwaukee, Wis., a

corporation of New York 3 Claims.

This invention relates to vacuum type seam testing apparatus.

An object of the invention is to provide testing apparatus whereby avacuum is produced over a portion of a seam and the leaks in saidportion detected by observing, after the release of the vacuum, thepresence of air bubbles in a liquid previously applied to the seam andhaving a sufficiently high viscosity to retain the bubbles for aconsiderable period of time.

Another object of the invention is to provide seam testing apparatuswhich eliminates the necessity of observing the seam during the intervalwhen the vacuum is applied.

Another object of the invention is to provide means for easily andrapidly applying a viscous liquid to a portion of the seam to be testedand for removing said liquid after the completion of the testingoperation.

Another object of the invention is to provide a seam testing apparatuswhich is sufficiently strong to withstand a high vacuum over a largearea and which has no windows or other easily breakable parts.

Another object of the invention is to provide apparatus which may beused to test the seams of vertical and overhead surfaces.

The apparatus, in gen ral, comprises a hood member adapted with suitablegaskets to be sealed over a portion of the seam to be tested, asuction-pressure flask in communicating relation with the hood andoperable to apply a viscous liquid to the seam and to remove the sameafter the testing operation, and means to evacuate the hood and causeair to enter through apertures in the seam and form bubbles in theliquid. The top of the hood is removable so that the bubbles, which areretained for a considerable period of time due to the viscosity of theliquid, may be observed and the presence of leaks thereby detected. Inanother embodiment of the invention, the viscous liquid is merelybrushed on the seam and the retained bubbles observed by removing theentire hood after the release of the vacuum.

Other objects and advantages will be set forth more fully in thefollowing description of embodiments of the invention illustrated in theaccompanying drawings.

In the drawings:

Figure l is a top plan view of the seam tester, showing the cover inopen position;

Fig. 2 is a cross section taken along line 2-2 of Fig. 1; and

Fig. 3 is a cross-sectional view of an embodiment wherein the top of thehood is not removable and the viscous liquid is merely brushed on theseam to be tested.

Referring to the drawings and particularly to the embodiment of theinvention illustrated in Figs. 1 and 2, a hood member I having aremovable cover 2 is shown with its open bottom portion applied to aseamed surface 3 of the object to be tested. A suction-pressure flask 4containing a viscous liquid 5 communicates through a pair of flexibletubes 6 and 1 with the hood I and serves to alternately apply the liquid5 to the seamed surface 3 within the hood I and to remove the sametherefrom as will be described subsequently.

The hood I, which may be of generally rectangular shape, is preferablysealed by means of soft rubber O-rings 8 disposed in correspondinggrooves 9 in its upper and lower edges. The O-rings are of circularcross section and'protrude above their corresponding edges forengagement with the cover 2 and seamed surface 3. When a vacuum iscreated within the hood I the outside air pressure forces the cover 2downwardly, causing the O-rings 3 to assume generally elliptical crosssections and efiiciently seal the hood to air and liquid tightness.

The hood .and cover 2 are made of metal or other unbreakable andnon-transparent,material and are sufiiciently strong to withstand thepressure caused by the creation of a relatively high vacuum within thehood I.

To provide for the ready inspection of the liquid 5 after the release ofthe vacuum, a handle If] is attached to one edge of the cover 2 andsuitable hinges II are secured to the otheredge thereof and to thecorresponding edge of the hood I.

Referring to Fig. 2, the liquid tube 6 is connected to a two positiondouble-acting valve l2 and extends therefrom through a fitting I3 in onewall of the hood I for termination closely adjacent the seamed surface 3to be tested for leaks. The tube 7, which is also connected to the valveI2, passes through a twohole stopper I4 in the neck of the flask 4 andis immersed a substantial distance beneath the surface of the liquid 5.Accordingly, the creation of a suction or pressure within the flask 4may operate to transfer the liquid, via the tubes 6 and 1 and the valveI2, between the flask 4 and the hood I.

The hood I is evacuated during the testing operation by means of avacuum pump, not shown, which is connected through a valve I2 and a tubeI5 to a fitting I6 disposed in a Wall of the hood 3 I above the level ofthe liquid 5. In addition to its ports for the vacuum pump and the tubes6, I, and I5, the valve I2 is provided with an opening to the air sothat the vacuum in the hood I may be released for easy opening of thecover 2.

The valve I2 is constructed with a pair of internal passages I1 whichare arranged so that when the valve is turned to its vacuum position, asshown in Fig. 2, the line to the vacuum pump is connected with the tubeI but the tubes 6 and 1 are not in communication with each other. Whenthe valve I2 is turned counterclockwise to its air-liquid position, thetube I5 is connected with the air opening and the liquid lines 6 and Iare in communicating relationship.

Because of the described construction of the valve I2, the hood I may beevacuated without the necessity of evacuating the flask 4. In addition,the cover 2 may be left down while the liquid 5 is transferred betweenthe flask 4 and the hood I. This is because the air opening in the valveI2 eliminates the possibility of back pressures as the level of theliquid in the hood I is raised or lowered.

In order to provide for the creation of either a vacuum or a pressurewithin the flask i, a tube I8 is inserted a slight distance through thestopper I4 and connected via a three position valve I9 to suitablesources of pressure and vacuum, not shown. The turning of the valve I9to its pressure position causes the liquid 5 to be forced through thetubes 6 and 1 and into the hood I, whereas the turning of the valve I9to its vacuum position causes the liquid 5 to be sucked back into theflask 4. The third position of valve I9 is its 01f position,,wherein thetube I8 is blocked and neither a vacuum nor a pressure is created.

When the hood I is evacuated after application of the liquid 5 to theseamed surface 3 within the hood, the resulting pressure differentialcauses air to enter through any leaks in said surface, for examplethrough pin holes in the butt weld 20 shown in the drawings.Accordingly, bubbles are formed in the liquid 5 above each leak andretained, due to the viscosity of the liquid, until they are observed bythe operator of the device after the release of the vacuum and thelifting of the cover 2.

It is important that the liquid 5 have sufficient viscosity to enable itto retain the bubbles for a considerable period of time. On the otherhand, the liquid must not be so thick that the leaks are in eifectsealed and the entrance of air prevented. Various gelatinous liquids maybe used, as well as oil, syrup, etc. Soap solutions may also be used ifthe percentage of soap is sufiiciently high.

The liquid used is preferably transparent, so that the small bubblesfrozen in the body of the liquid may be easily observed. Where theliquid is not transparent the presence of leaks is determined by notingthe presence of bubbles on the surface thereof.

It has been found that a transparent, colorless mineral oil of aviscosity equivalent to S. A. E. '70 subjected to a vacuum of 28 inchesof mercury produces the desired results. For average work, the vacuum ismaintained for a period of one to five minutes. However, where maximumfreedom of porosity is essential a more viscous liquid should be usedsubjected to higher vacuums for greater periods of'time.

The operation of the seam testing apparatus is as follows: assume thatthe hood I has been positioned. on the seamed surface 3. and thatthecover 2 is down and in engagement with one of the O-rings 8. Theoperator then turns the valve I9 to its pressure position and the valveI2 to its air-liquid position, causing the viscous liquid 5 to flowthrough the tubes 6 and. 1 and fill the hood I to a depth ofapproximately an eighth of an inch.

The operator next turns valve I9 to off and the valve I2 to vacuum,causing the evacuation of the hood I and the formation of bubbles in theliquid 5 as previously described.

Valve I2 is then turned to its air-liquid position and air is admittedto the hood I to release the vacuum. The cover 2 of the hood is thenlifted and the location of the retained bubbles noted so that thecorresponding leaks in the weld 20 may be repaired at a later time.

The cycle is completed by turning the valve I9 to vacuum and sucking theliquid 5 back into the flask 4, after which the operator moves theapparatus to another portion of the seam and repeats the operation.

Referring to the embodiment of the invention illustrated in Fig. 3, agenerally rectangular hood 2| is formed with a cover portion 22 which isintegral with the walls of the hood 2I and is therefore not removable.The hood 2i is sealed to the seamed surface 3 by means of an O-ring 23which corresponds to the lower O-ring 8 of the first embodiment andfunctions in the same way.

To provide for the evacuation of the hood, a hose 2d is connectedbetween a fitting 25 in the cover portion 22 and a two-position valve 26in the line of a vacuum pump, not shown. When the valve 26 is in oneposition the hose 24 communicates with the vacuum pump and a vacuum iscreated within the hood 2 I, whereas the turning of the valve 25 to itsother position admits air to the hood 2I and releases the vacuumtherein.

In operating the apparatus, a thin layer of viscous liquid is applied bybrushing or similar means to a portion of the seamed surface 3 to betested. The hood 2| is then placed in position and evacuated, causingair to enter through leaks in the seam and form bubbles on the surfaceof the liquid. These bubbles remain, due to the properties of the liquidused, until the operator releases the vacuum, lifts the hood 2|, andnotes the location of the leaks.

The liquid used may in most cases be the same as that selected for thefirst embodiment, with a high surface tension being a desirableproperty. A thick soap solution, which retains its bubbles for asubstantial interval of time, has been found to be one of the bestliquids to use.

The use of a thin layer of viscous liquid is particularly advantageouswhere it is desired to test vertical or overhead seams. In theseapplications it is desirable to use a hood made of a light material suchas plastic or rubber, so that the operator may manipulate the apparatuswithout excessive fatigue.

The apparatus described in connection with both embodiments of theinvention provides a simple means for testing a seam Without thenecessity of observing the seam during the period when the vacuum isapplied. Consequently, there is no need for breakable parts such aswindows, and the apparatus may be made unbreakable, particularly whenthe flask 4 is made of metal instead of glass.

The hoods I and 2| may be made of either metal, for high rigidity andpressure resistance, or flexible material such as rubber or plastic, for

ability to test various shapes and types of curved seams.

Although only one shape of hood has been shown in the drawings, manyother shapes may be used in special applications such as in the testingof corners, edge seams, etc.

Various embodiments of the invention may be employed within the scope ofthe accompanying claims.

I claim:

1. In a vacuum operated apparatus for testing the Welded surface ofmetallic articles to ascertain Whether there are any leaks therein, acover member adapted to be sealed in spaced relation with the weldedsurface to be tested and to create with said welded surface a fluidtight chamber, a substance for application to said surface within saidchamber in a layer of pre-determined thickness, said substance having ahigh surface tension and a viscosity low enough to permit entrance ofair into the substance but high enough to trap air in the substance inthe form of bubbles with said bubbles remaining frozen for observation aconsiderable length of time after forming and after the evacuation ofthe chamber is completed and the vacuum is broken, and means to evacuatesaid chamber to draw air throu h leaks in said surface into thesubstance and form said bubbles therein.

2. In vacuum operated apparatus for testing the welded surface ofmetallic articles to ascertain whether there are any leaks therein, acover member adapted to be sealed in spaced relation with the weldedsurface to be tested and to create with said welded surface a fluidtight chamber, a transparent colorless mineral oil for application tosaid surface within said chamber in a layer of predetermined thickness,said oil having a viscosity equivalent to S. A. E. 70, said viscositybeing low enough to permit entrance of air into the oil but high enoughto trap air in the oil in the form of bubbles with said bubblesremaining frozen for observation a considerable length of time afterforming, and means to evacuate said chamber under a vacuum ofapproximately 28 inches of mercury to draw air through leaks in saidsurface into the oil and form said bubbles therein.

3. Vacuum operated apparatus for testing the welded surface of metallicarticles to ascertain whether there are any leaks therein, whichcomprises a hood member having depending sides extending downwardly fromthe top of the hood toward the welded surface to space the top of thehood from the welded surface and provide a chamber between the hood andwelded surface, gasket means disposed between the hood and surface toseal off the chamber, a pressure vessel, a liquid stored in saidpressure vessel for application to said surface within said chamber in alayer of predetermined thickness, said liquid having a high surfacetension and a viscosity low enough to permit entrance of air into theliquid but high enough to trap air in the liquid in the form of bubbleswith said bubbles remaining frozen for observation a considerable lengthof time after forming and after the evacuation of the chamber iscompleted, a double acting valve having a vacuum and an air liquidposition, a tube connecting the pressure vessel and valve, a suctiontube connecting the hood and valve, and a pressure tube connecting thehood and valve, a second valve connected to said pressure vessel, meansto operate said second valve to apply pressure to said pressure vesselwhen the double acting valve is in air liquid position to force liquidfrom the vessel into the hood chamber and into contact with the weldedsurface and to apply vacuum to said pressure vessel to withdraw liquidfrom the chamber back into the vessel, means to actuate said doubleacting valve to vacuum or air liquid position, and a vacuum pumpconnected to the double acting valve to evacuate the hood chamber whenthe double acting valve is in vacuum position and draw air through leaksin said surface into said liquid and form said bubbles therein.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,490,670 Law Apr. 15, 1924 2,108,176 Newby Feb. 15, 19382,255,921 Fear Sept. 16, 1941

